Ernest Hemingway's unrequited love out in open!

A set of unpublished letters from the iconic American writer to a German singer-actress reveals some heartrending truth.

To him she was "my little Kraut", or "daughter", to her he was simply "Papa" - and it was love at first sight when they met aboard a French ocean liner in 1934. A set of 30 unpublished letters and telegrams from the legendary American writer Ernest Hemingway to the German singer-actress Marlene Dietrich, which have been made public for the first time, reveal the depth of their passion for each other - although theirs was a relationship in which they never went to bed together.

Hemingway and Dietrich started writing to each other when he was 50 and she was 47, remaining in close contact until the writer's suicide in 1961. But they never consummated their love, because of what Hemingway referred to as "unsynchronised passion".

Although it was not a physical relationship, they certainly knew how to flirt. In a letter dated June 19 1950 at 4am, Hemingway wrote: "You are getting so beautiful they will have to make passport pictures of you 9 feet tall."

He continued with a question: "What do you really want to do for a life work? Break everybody's heart for a dime? You could always break mine for a nickel and I'd bring the nickel." Another time he wrote: "I can't say how every time I ever put my arms around you I felt that I was home." He ends a letter: "I love you and I hold you tight and kiss you hard."

In 1951 he wrote to her from the tropical heat of Cuba where he was trying to write The Old Man and the Sea. "It was too hot to make love, if you can imagine that, except under water and I was never very good at that."

The correspondence has now been released by the Kennedy Library in Boston on the instructions of Dietrich's daughter, Maria Riva, who wanted the letters to be kept under wraps for 15 years after her mother's death. Tom Putnam, director of the Kennedy Library, said: "When combined with the library's collection of correspondence from Dietrich to Hemingway, these new letters help to complete the story of a remarkable friendship between two exceptional individuals."

The couple met in 1934 on a French luxury liner, the Ile de France, when Hemingway was returning to Key West via Paris after a safari in east Africa, and Dietrich was travelling back to Hollywood after visiting relatives in Nazi Germany on one of her last trips home. Much later Hemingway revealed to a friend why he believed the relationship had never been consummated.

"Victims of unsynchronised passion. Those times when I was out of love, the Kraut was deep in some romantic tribulation, and on those occasions when Dietrich was on the surface and swimming about with those marvellously seeking eyes, I was submerged."

"There are now plans to put their correspondence into a book, including 31 letters from Dietrich to Hemingway. In one of them from 1951, she addressed him as "Beloved Papa", and continued: "I think it is high time to tell you that I think of you constantly. I read your letters over and over and speak of you with a few chosen men. I have moved your photograph to my bedroom and mostly look at it rather helplessly." Their letters reveal the insecurities and fears of both, and frequently touch on Hemingway's lifelong fight against depression. "Toi and moi have lived through about as bad times as ever were," he wrote in June 1950.

"I don't mean just wars. Wars are spinach. Life in general is the tough part." Dietrich made no secret of her dislike of physical relationships. In that sense she might not have been a bad match for Hemingway, despite his womanising reputation.

Referring to his fourth wife, Mary Welsh, in a 1950 letter, he wrote: "Mary is still the best woman in the bed that I have ever known. Of course I have not been around much and am basically shy."